Numerical simulation of ambient seismic wavefield modification caused by pore-fluid effects in an oil reservoir
Numerical simulation of ambient seismic wavefield modification caused by pore-fluid effects in an oil reservoir
复制标题
DOI：
10.1190/geo2011-0513.1
复制
发表时间：
2013
期刊：
影响因子：
3.3
通讯作者：
M. Lambert;E. Saenger;B. Quintal;S. Schmalholz
中科院分区：
文献类型：
--
作者：
M. Lambert;E. Saenger;B. Quintal;S. Schmalholz
我们已经模拟了数值地震响应的孔隙弹性夹杂物的适用于与周围波场相互作用的油藏的属性。该模型包括由介观尺度（即，厘米到米的数量级）不均匀性。我们使用宏观尺度上的黏弹性近似来实现介观尺度理论在公里尺度上波传播的数值模拟中产生的衰减和频散。这种放大方法包括波致流体流动的有限元建模，以确定多孔弹性介质的有效地震特性，例如P波和S波的衰减。在有限差分波传播模拟中实现了拟合的等效粘弹性行为。通过这两个阶段的过程，我们模拟了千米尺度上的准孔隙弹性波传播，并研究了流体性质和流体饱和度对模拟地震振幅的影响。特别是，我们解决了一个问题，是否在油藏中的孔隙弹性效应可能是一个合理的解释低频环境波场的修改，近年来在油田观察到。我们的研究结果表明，环境波场的修改预计会发生油藏表现出高衰减。然而，在地表记录中是否可以检测到这种修改将取决于采集设计和噪声减轻处理以及特定于场地的条件，例如地下的地质复杂性、环境波场的性质和地表噪声的量。
We have modeled numerically the seismic response of a poroelastic inclusion with properties applicable to an oil reservoir that interacts with an ambient wavefield. The model includes wave-induced fluid flow caused by pressure differences between mesoscopic-scale (i.e., in the order of centimeters to meters) heterogeneities. We used a viscoelastic approximation on the macroscopic scale to implement the attenuation and dispersion resulting from this mesoscopic-scale theory in numerical simulations of wave propagation on the kilometer scale. This upscaling method includes finite-element modeling of waveinduced fluid flow to determine effective seismic properties of the poroelastic media, such as attenuation of P- and S-waves. The fitted, equivalent, viscoelastic behavior is implemented in finite-difference wave propagation simulations. With this twostage process, we model numerically the quasi-poroelastic wave-propagation on the kilometer scale and study the impact of fluid properties and fluid saturation on the modeled seismic amplitudes. In particular, we addressed the question of whether poroelastic effects within an oil reservoir may be a plausible explanation for low-frequency ambient wavefield modifications observed at oil fields in recent years. Our results indicate that ambient wavefield modification is expected to occur for oil reservoirs exhibiting high attenuation. Whether or not such modifications can be detected in surface recordings, however, will depend on acquisition design and noise mitigation processing as well as site-specific conditions, such as the geologic complexity of the subsurface, the nature of the ambient wavefield, and the amount of surface noise.